Question: "Why does the Old Testament Law say so much about mildew?"

Answer: A lot of modern homes have mold or mildew problems, and it is a health concern, as exposure to mildew affects our bodies in adverse ways. The Bible speaks on the subject of mold in Leviticus 14:33–48. The original word translated “mildew” or “mold” in this passage is literally the word for “leprosy.” God wanted His people to live in a mold-free environment, showing His concern for their well-being.

We know today that the presence of mold or mildew in a house contributes to allergies, asthma, bronchitis, and other breathing difficulties. The Mosaic Law commanded the Israelites to remove mildew from their houses and gave step-by-step instructions on how to do it. The Lord had them take preventative measures to protect their health. Then as now, getting rid of mold was important.

God spoke to Moses to give the instructions on what to do when the Israelites moved into Canaan and encountered mold in a house: the owner of the house was to tell the priest about the mold (Leviticus 14:35). The priest would then order the house to be emptied, and he would go in and inspect the house. If the mold had greenish or reddish streaks and appeared to run below the surface of the wall, then the priest would quarantine the house for seven days (verses 36–38). During the quarantine, anyone who entered the house would be ceremonially unclean until evening; anyone who slept or ate in the house must wash his or her clothes (verses 46–47).

After the one-week quarantine, the priest would reexamine the house. If the mold had spread, then more drastic steps were taken: “He is to order that the contaminated stones be torn out and thrown into an unclean place outside the town. He must have all the inside walls of the house scraped and the material that is scraped off dumped into an unclean place outside the town. Then they are to take other stones to replace these and take new clay and plaster the house” (Leviticus 14:40–42). Another period of quarantine followed.

After the removal of the infected parts of the house, the priest would return for yet another inspection. If the mold had reappeared on the new plaster, the priest would declare it to be “a persistent defiling mold” and the house itself “unclean” (Leviticus 14:44). There was only one thing left to do in that case: “It must be torn down—its stones, timbers and all the plaster—and taken out of the town to an unclean place” (verse 45).

If, however, the mold or mildew had not spread after the remodel, the priest would pronounce the house “clean” (Leviticus 14:48). The house would then be ceremonially purified in a unique ritual involving two birds, water, cedar wood, scarlet yarn, and a clay pot (verses 49–53).

Another reason, besides physical health, for the Bible’s discussion of mildew (or “leprosy”) in a house could be that it is a graphic illustration of sin. Like leprosy in the skin, mildew in a house is destructive, unwholesome, and unclean. The Old Testament Law taught that mildew, like sin, had a debilitating influence in a person’s home. Like sin, it would spread. Like unchecked sin, it would lead to total destruction. And, like sin, it could only be eradicated through the agency of a priest with a blood sacrifice.